1. Field of the Invention
This invention relates to a device for laying a thin metal wire in a straight line on the surface of the thermoplastic film of a laminated glass pane, the device comprising a rotatable mounting for the wire supply reel, a heated pressing roller for pressing the wire into the thermoplastic film and guide device for the wire between the supply reel and the pressing roller.
2. Description of the Related Art
A device of this kind is known, for example, from DE 20 43 706 B2. In this case, the wire laid into the plastic intermediate film of a laminated glass pane is intended to serve as an antenna wire, but a laying device of this construction is also suitable for laying thin metal wires which serve other purposes. For example, resistance wires for the manufacture of heated glass panes can be laid with such a laying device, as can metal wires which serve solely for decorative purposes.
The metal wires commonly used in the manufacture of heatable laminated glass panes are extremely thin. As a rule, wires of tungsten having a diameter of about 20 micrometers are used for this purpose. It is very difficult to lay such thin wires by means of the conventional device in an absolutely rectilinear array. In particular, it has been found that the mechanical behavior of the wires to be laid is not always constant, but that the wires frequently possess elastic stresses which can lead to uncontrolled deformations in the laying of the wire. Deviations of the wires from the straight line are found to be particularly annoying to the human eye when the wires are laid at a comparatively small spacing in a parallel arrangement, which occurs, for example, in the case of electrically heatable laminated glass panes.